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Linux, Ubuntu 10.04.1 LTS

I have a (quite old) server (Dell PowerEdge 1650) with two CPUs. I have used it for over a year without any problems.

One week ago the server crashed, I was unable to find any errors in any logs, i rebooted and everything seemed to work well. Two hours later when i had upgraded the OS i noticed that I could only see one CPU.

$ cat /proc/cpuinfo | grep processor

processor : 0

I rebooted several times, and once, only once the system found two CPUs.

What do you think? Are we talking about broken software or hardware? I can't see anything wrong during boot, BIOS shows what i have "Two 1266 MHz Processors".

One theory is that one CPU is dead, but if that was the case shouldn't BIOS complain? The server was moved two weeks ago, maybe one CPU is not correctly connected to the socket?

I have no idea where to begin to debug this, any ideas?

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Try to reboot using the ubuntu Live CD. Check how many CPUs the system will recognise. –  Khaled Dec 15 '10 at 15:16
    
Yes, I intend to do that next time i have physical access to the machine (maybe in a week or so). Anything I can try remotely? –  nsg Dec 15 '10 at 15:47
    
Run 'dmesg' to see whats detected on bootup. –  Rafiq Maniar Dec 15 '10 at 16:03
    
SMP: Allowing 2 CPUs, 0 hotplug CPUs; Initializing CPU#0; [ 0.087431] CPU0: Intel(R) Pentium(R) III CPU family 1266MHz stepping 01 [ 0.088001] Booting processor 1 APIC 0x0 ip 0x6000 [ 5.060621] Not responding. [ 5.060801] Brought up 1 CPUs –  nsg Dec 16 '10 at 9:53
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2 Answers

If you had an OS upgrade when CPU disappeared be sure that you are running now a SMP kernel:

[vitalie@silver ~]$ uname -srv
Linux 2.6.18-194.26.1.el5 #1 SMP Tue Nov 9 12:54:20 EST 2010
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Linux 2.6.32-26-generic-pae #48-Ubuntu SMP Wed Nov 24 10:31:20 UTC 2010 –  nsg Dec 16 '10 at 9:36
    
You are runngin a SMP kernel, from the dmesg output this seems to be a hardware problem. –  vitalie Dec 16 '10 at 11:21
    
Yes, it seems thats the case :\ –  nsg Dec 20 '10 at 11:19
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If you have "dmidecode" program - run it and check

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Yes, I have it installed. See d.nsg.cc/dmidecode.txt for output. –  nsg Dec 16 '10 at 9:45
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